JPH11209167A - Low expansion feldspar-based porcelain and its adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low expansion feldspar-based porcelain and a method for preparing the low expansion feldspar porcelain which can be used in combination with a metal or a porcelain having a low coefficient of thermal expansion. SOLUTION: A continuous vitreous matrix phase, cesium,
Cubic leucite stabilized by at least one of calcium, strontium, barium, or thallium, comprising a discontinuous crystalline phase that is uniformly dispersed and having a melting temperature of about 800 ° C to about 1200 ° C. A feldspathic porcelain composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feldspar porcelain having a low coefficient of thermal expansion, a method for producing the low expansion feldspar porcelain, and a dental restoration including the low expansion feldspar porcelain. The present invention, in particular,
The present invention relates to low expansion feldspar porcelain including cubic leucite, a simple and efficient method for preparing said porcelain, and dental restoration including said porcelain.

[0002]

BACKGROUND OF THE INVENTION Leucite is a stable form of crystalline potassium aluminosilicate and has a tetragonal configuration at room temperature. Tetragonal leucite is also known as "low-temperature leucite" and has been used as a reinforcement in feldsparous dental porcelain. Such dental porcelain materials, for example,
U.S. Pat. Nos. 4,604,366 and 4,798,
No. 536. Since tetragonal leucite has a high coefficient of thermal expansion, feldspathic porcelain containing leucite dispersed as a discontinuous layer has a correspondingly high coefficient of thermal expansion. For example, Jeneric / Pentron
Inc. (Wallingfor, Connecticut
d) using tetragonal leucite-containing feldspar-like porcelain powder sold under the trademark OPTEC (trademark) at 50 ° C.
From about 18.6 when measured in the range from
A dental porcelain block having a thermal expansion coefficient of × 10 ⁻⁶ / ° C. can be obtained.

[0003] When heated to about 625 ° C, tetragonal leucite changes to a cubic polymorph and shows a 1.2% volume change. This transition is reversible, and upon cooling, the cubic leucite crystals return to the more stable tetragonal polymorph. In contrast to tetragonal leucite, the stabilized cubic phase of leucite is known as "hot leucite" and is unstable at room temperature, but is
It has a coefficient of thermal expansion of about 3 × 10 ⁻⁶ / ° C. when measured in the range of 0 ° C.

[0004] "Crysta" by Rouf et al.
lization of Glasses int
he Primary Field of Leuci
tein the K ₂ O-Al ₂ O ₃ -SiO ₂ Sys
tem ", Trans. J. Brit. Ceram. S
oc. , 77: a 36-39 (1978), for both powdered and bulk samples, TiO _2, Zr as a catalyst
Using O ₂ and P ₂ O ₅ , K ₂ O—Al ₂ O ₃ —SiO
A constant temperature heat treatment method for crystallizing cubic leucite in a highly viscous system of ₂ is described. Rough et al.
This method requires a long time at a high temperature, and is a method in which cubic leucite is formed as a single crystal phase by K ₂ O (about 18% by weight) present in a large amount in the raw glass composition. Bulk samples of porcelain produced by the method of Laf et al. Do not contain cubic leucite, which is virtually uniformly dispersed therein.

[0005] "On the Crystallatio" by Hermansson et al.
n the of Glassy Phase in
Whitewares ", Trans. J. Brit.
Ceram. Soc. 77: a 32-35 (1978), a heat treatment method of crystallizing cubic leucite in the high viscosity system _{K 2 O-Al 2 O 3} -SiO 2 are disclosed as well. According to the disclosure of Hermanson et al., To stabilize the cubic phase of leucite at room temperature,
A high content of K ₂ O, a long heating time and a low content of CaO (about 1% by weight) are required.

[0006] "Cr" by Prasad et al.
ystallation ofCubic Leu
cite By Composition Addit
ives ”, 19th Annual Session
n, American Association Fo
r Dental Research, (1990)
Describes a bulk crystallization method for stabilizing cubic leucite at room temperature by adding cesium oxide to a feldspathic composition. This method comprises the steps of heating a raw material mixture containing cesium oxide at 1550 ° C. for 8 hours, rapidly cooling the melt to 1025 ° C., keeping the resulting material at a constant temperature for 1 to 4 hours, Performing bulk crystallization of the olivine crystal;
Thereafter, allowing the composition to cool in air.
including. According to Prasad et al., The composition consists of a mixture of cubic leucite and tetragonal leucite, is a highly heat-resistant material and can only be melted at temperatures above 1200 ° C. .

[0007] None of the prior art methods described above disclose an ion exchange step.

[0008]

It is well known in the art that it is important that the coefficient of thermal expansion of a dental porcelain exactly matches the coefficient of thermal expansion of the metal or porcelain material with which the dental porcelain contacts. is there. Prior art white porcelain-containing dental porcelain generally has a high coefficient of thermal expansion, so these dental porcelains are:
It cannot be used in combination with a material having a significantly lower coefficient of thermal expansion. For example, Jeneric / Pen
tron, Inc. (Wallin, Connecticut
gford) sells Slippery Gla
Low expansion coefficient porcelain lining materials such as ss (registered trademark) porcelain
Jenicic / Pentron, Inc. (Wallingford, Connecticut)
It cannot be used with prior art high thermal expansion leucite containing porcelain, such as PTEC ™.

It is, therefore, an object of the present invention to provide a low expansion feldspar porcelain and a method by which low expansion feldspar porcelain can be produced. It is a further object of the present invention to provide a cubic leucite-reinforced feldspathic dental porcelain composition that can be used in combination with a low expansion material in dental restorations.

[0010]

The present invention is directed to a feldspathic porcelain composition comprising a continuous vitreous matrix phase, cesium,
A substantially uniformly dispersed discontinuous crystalline phase comprising cubic leucite stabilized by at least one of calcium, strontium, barium, or thallium; It is characterized by having a melting temperature of up to ° C.

The cubic leucite has an average diameter in the range from about 0.5 μm to about 10 μm, in particular about 1 μm.
It is desirable to have an average diameter ranging from m to about 4 μm.

It is preferable that the discontinuous crystal phase accounts for about 5% to about 65% by weight of the feldspathic porcelain composition.

Further, the feldspathic vitreous matrix phase may comprise from about 65% to about 72% by weight of SiO ₂ , from about 10% to about 15% by weight of Al ₂ O ₃ , from about 5% to about 5% by weight. K ₂ O up to 10% by weight, and about 5% to about 1%
Desirably, it contains up to 0% by weight of Na ₂ O.

Further, the feldspathic vitreous matrix phase further comprises about 0% to about 2% by weight of CaO, about 0% to about 0.5% by weight of MgO, and about 0% to about Desirably, it contains up to 0.5% by weight of CeO ₂ and about 0% to about 0.5% by weight or less of Li ₂ O.

Another invention is a method for preparing a feldspathic porcelain composition, comprising a vitreous material comprising SiO ₂ , Al ₂ O ₃ and K ₂ O, and rubidium, cesium, calcium, strontium, barium, Or forming a metal salt of at least one metal of thallium, and forming an alkali aluminosilicate powder containing at least one alkali metal salt, heating the alkali aluminosilicate powder, from alkali cations and the metal salt Performing ion exchange with the released metal cations to produce a feldspathic porcelain composition having a continuous vitreous matrix phase and a discontinuous crystalline phase including cubic leucite. It is characterized by.

Preferably, the metal salt is rubidium nitrate.

Still another invention is a method for preparing a feldspar-like porcelain composition, comprising a vitreous material containing SiO ₂ , Al ₂ O ₃ , K ₂ O and Na ₂ O, and cesium, calcium, strontium. Forming an alkali aluminosilicate powder containing at least one metal salt of barium, or thallium; and heating the alkali aluminosilicate powder to form an alkali cation and a metal cation released from the metal salt. Performing ion exchange to produce a feldspathic porcelain composition having a continuous vitreous matrix phase and a discontinuous crystalline phase including cubic leucite.

The alkali aluminosilicate powder may be
Further, it is desirable to include an alkali metal salt.

Further, the alkali metal salt is preferably present in an amount ranging from about 1% to about 10% by weight of the metal salt.

Further, it is preferable that the alkali aluminosilicate powder is formed by mixing the vitreous material and the metal salt in a weight ratio of about 20:80 to about 80:20.

Furthermore, the feldspathic glass, Si0 ₂ from about 65% to about 72 wt%, Al ₂ O ₃ from about 10% to about 15 wt%, about 5% to about 10 wt% K ₂ O, and optionally from about 5% to about 10% by weight.
It is desirable to include up to Na ₂ O by weight.

Further, the feldspathic glass is about 0% by weight.
To about 2% by weight of CaO, from about 0% to about 0.5% by weight.
MgO up to weight percent, it is desirable to include Li ₂ O of CeO ₂ from about 0 wt% to about 0.5 wt%, and from about 0 wt% to about 0.5 wt%.

These and further objects of the present invention have been achieved by a process for producing a feldspar-based porcelain composition, which comprises SiO ₂ , Al ₂ O ₃ , K ₂ O, and Na ₂ O,
Forming an alkali aluminosilicate containing at least one metal salt of rubidium, cesium, calcium, strontium, barium, thallium and a mixture thereof; and heating the powder to obtain alkali cations and the metal released from the metal salt. Performing ion exchange with cations to form a feldspathic porcelain composition having a continuous vitreous matrix phase and a discontinuous crystalline phase including cubic leucite.

The resulting feldspathic porcelain composition generally has a viscosity of about 8 × when measured in the range of 50 ° C. to 550 ° C.
It has a coefficient of thermal expansion in the range of 10 ⁻⁶ / ° C. to about 16 × 10 ⁻⁶ / ° C. The cubic leucite present in the discontinuous crystalline phase has an average diameter ranging from about 0.25 μm to about 10 μm. The discontinuous crystalline phase is present in a range from about 5% to about 65% by weight of the composition and is substantially uniformly dispersed throughout the vitreous matrix phase.

The feldspathic porcelain composition according to the invention can be used in the manufacture of a wide range of dental restorations. In one embodiment, the feldspathic porcelain composition is used as a low expansion core of an all-ceramic dental restoration. In another embodiment, the feldspathic porcelain composition can be melted into a low expansion metal alloy framework or low expansion core to form a smooth coating thereon. In yet another embodiment, the feldspathic porcelain composition can be used to make inlays, onlays, or veneers. The term “low expansion” is used herein to refer to 50 ° C. to 550 ° C.
It should be understood that, when measured in the range of ° C., it refers to a coefficient of thermal expansion ranging from about 8 × 10 ⁻⁶ / ° C. to about 16 × 10 ⁻⁶ / ° C.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The alkali aluminosilicate powder first formed by the practice of the present invention is SiO ₂ , Al ₂ O
₃ , a mixture of feldspathic glass frit comprising K ₂ O and Na ₂ O and at least one metal salt of rubidium, cesium, calcium, barium or thallium. In one embodiment, the alkali aluminosilicate powder comprises about 65% to about 72% by weight SiO ₂ , about 9% to about 15% by weight Al ₂ O ₃ , about 5% by weight
To about 16% by weight K ₂ O, and about 0.5% by weight
A feldspathic glass frit containing Na ₂ O up to about 10% by weight, metal salt from about 20 wt% to about 80 wt% (based on the total weight of the aluminosilicate alkali powder)
And, if present, the remaining components of the powder, the remaining components being, for example, NaNO ₃ , Na ₂ CO ₃ , Li
_{2 O, BaO, CaO, Mg0} , CeO 2, B 2 0 3, Zr
O _2, Ti0 _2, ZnO, is BiO ₂ and P ₂ 0 _5, but not limited thereto. Preferably, the alkali aluminosilicate powder is formed by mixing feldspathic glass with a metal salt. Feldspar glass contains SiO ₂ , Al ₂ O ₃ , K ₂ O, and Na ₂ O as components,
Usually, for example, Li ₂ O, BaO, CaO, MgO,
_{CeO 2, B 2 0 3,} ZrO 2, Ti0 2, ZnO, BiO 2
And it contained in combination with other components such as P ₂ 0 _5. Feldspar glass is known and is commercially available. In a preferred embodiment, the feldspathic glass frit comprises from about 68.5% to about 71.0% SiO 2 by weight.
₂ , from about 12.0% to about 13.5% by weight of Al ₂
O ₃ , from about 6.5% to about 10.5% by weight of K
₂₀ from about 6.0% to about 9.5% by weight of Na
₂ O, from about 0.15% to about 2.0% by weight of Ca
O, including CeO ₂ of Mg0 from about 0 wt% to about 0.5 wt%, and from about 0 wt% to about 0.4 wt%. In a particularly preferred embodiment, the feldspathic glass is
71.0 wt% SiO ₂ , 12.0 wt% Al
₂ O ₃ , 8.0 wt% K ₂₀ , 8.0 wt% Na ₂ O,
0.2 wt% of CaO, 0.4 wt% Mg0, and containing 0.4 wt% of CeO _2.

The metal salts used in the practice of the present invention can be selected from salts corresponding to the general formula MX, wherein M is rubidium, cesium, calcium, strontium, barium, and X is a metal cation selected from the group consisting of thallium, and X is an anion selected from the group consisting of nitrate, acetate, sulfate, carbonate, and chloride. Rubidium nitrate
It is particularly suitable for carrying out the method according to the invention. In the alkali aluminosilicate powder according to the present invention, a mixture of a metal salt and an alkali metal salt can be conveniently used to promote ion exchange. Without wishing to be bound by any theory or mechanism, a metal salt, such as, for example, rubidium nitrate, mixed in the presence of an alkali metal salt, such as sodium nitrate,
It is believed that the concentration gradient created by the metal salt in an amount ranging from about 1% to about 10% by weight causes the extraction of sodium from the feldspathic glass frit and facilitates the ion exchange process. In a highly preferred embodiment according to the present invention, use is made of rubidium nitrate, sodium nitrate and feldspathic glass having the following components:
Form an alkali aluminosilicate powder according to the practice of the present invention. The components of the feldspathic glass are as follows.

[0028]

[Table 1] Weight ratios of feldspathic glass to metal salt from about 20:80 to about 80:20 can be used to form alkali aluminosilicate powders according to the practice of the present invention. About 50:50
It has been found that a mixture of feldspathic glass and rubidium nitrate with a weight ratio of .gtoreq. Gives particularly good results, but other metal salts and / or other weight ratios are advantageously used in the process according to the invention. It is thought that it can be done.

After mixing the feldspathic glass with the metal salt in a suitable mixing ratio, the mixture can be made into a powder by a suitable technique, for example, grinding in a mortar. The resulting powder is placed in a furnace and is heated from about 200 ° C to about 900 ° C.
, Preferably to a temperature ranging from about 550 ° C to about 650 ° C. The duration of the heating step is about 4
It can range from hours to about 48 hours and can be run under vacuum or pressure, for example, in an autoclave or sealed tube, or at atmospheric pressure. The heating step causes the powder to melt, such that some or all of the metal cations, for example, sodium and potassium cations, and some or all of the metal cations released from the metal salts, for example, rubidium salts. Between all, ion exchange occurs. Those skilled in the art will understand that the choice of temperature will vary greatly depending on the melting temperature of the metal salt used. The selection of an appropriate temperature can be well implemented by those skilled in the art. Without wishing to be bound by any theory or mechanism, the metal cations diffuse into the vitreous matrix and crystallize for crystallization and growth of cubic leucite in the vitreous matrix. It is thought to act as a nucleating agent.

After performing the ion exchange heat treatment operation, the resulting powder is treated to remove virtually any unreacted metal salts present in the powder, yielding a purified powder. It should be understood that the expression "effectively removed" here means that no metal salt is detected by X-ray diffraction.
Suitable processing techniques for removing metal salts include, for example, dissolving or rinsing the powder with a suitable liquid, such as distilled water. The rinsing operation is repeated until no metal salt can be detected by X-ray diffraction. Thereafter, the resulting purified powder can be dried, for example, at 150 ° C. for 2 hours.

The ion exchange is a process utilizing a diffusion action, and is controlled by the heat treatment time as well as the heat treatment temperature. The ion exchange time determines the degree of cubic leucite crystallization in the low expansion feldspathic glass.

Thus, for example, in one embodiment according to the present invention, the ion exchange heat treatment is carried out at a relatively low temperature of about 200 ° C. to less than about 550 ° C. for about 4 ° C.
It can be carried out for a period ranging from hours to about 48 hours. Under such conditions, an amorphous material is obtained. FIG. 1 is a diagram showing an X-ray diffraction pattern of a powder sample produced according to Example 1 described below. According to FIG. 1, it is clear that the material obtained after the ion exchange heat treatment is amorphous.

Next, the amorphous material is placed in a furnace and heated, preferably under vacuum, to form a feldspathic porcelain according to the present invention. Preferably, the amorphous material starts at about 550 ° C. and ramps at a rate of about 0.5 ° C./min to about 55 ° C./min.
Heated in a temperature range up to ° C. When the maximum temperature is reached, the vacuum is released. After the vacuum is released, the powder may maintain the maximum temperature for about 0 to about 25 minutes, preferably about 1 to about 3 minutes. According to a preferred embodiment, the amorphous material may be prepared prior to heat treatment using known techniques, for example, by mixing the powdered amorphous material in a conventional dental porcelain fortifying solution to form a slurry, The slurry is concentrated in a split mold to form a preform having the desired dimensions, and is shaped as a bulk preform. next,
The resulting bulk preform can be further heated to form a feldspathic porcelain having a discontinuous crystalline phase in which the cubic leucite is substantially uniformly dispersed throughout the vitreous matrix phase.

FIG. 2 shows the X-ray powder diffraction pattern of the sample of FIG. 1 after such additional heat treatment, which clearly shows the presence of cubic leucite in addition to the vitreous matrix phase. It is. FIG. 3 shows a micrograph taken by a scanning electron microscope (SEM), which shows that there are no small twinned cubic leucite with an average diameter of about 0.5 μm to about 1 μm. The presence of crystals is confirmed. Only small amounts of twinned tetragonal leucite crystals may be formed when practicing the method according to the invention, the abundance being less than 0.05% by weight of the total composition. Conceivable.

According to one aspect of the present invention, the amount of the cubic leucite discontinuous crystalline phase can be controlled by adjusting the duration of the ion exchange heat treatment step. In particular, it has been found that the amount of crystalline phase increases with increasing duration of the ion exchange heat treatment (FIGS. 4-7).

One important advantage of the feldspathic porcelain compositions described herein is that the cubic leucite crystals present in the composition can be from about 0.5 μm to about 10 μm, preferably from about 0.5 μm to about 10 μm. Having an average diameter in the range of 1 μm to about 4 μm. Diameters greater than about 10 μm may provide an undesirable rough and uneven surface, abrade the natural dentition of a human, and cause discomfort or irritation in the oral cavity. The amount of cubic leucite produced is from about 5% to about 65% by weight, based on the total weight of the feldspathic porcelain composition, typically
It ranges from about 20% to about 50% by weight. The amount of cubic leucite may exceed about 65% by weight of the total composition weight. The coefficient of thermal expansion of the resulting cubic leucite composition is generally from about 8 × 10 ⁻⁶ / ° C. to about 16 × 10 ⁻⁶ when measured at 50 ° C. to 550 ° C.
/ ° C., preferably from about 8 × 10 ⁻⁶ / ° C. to about 1 × 10 ⁻⁶ / ° C.
The range is up to 2 × 10 ⁻⁶ / ° C. In contrast, prior art feldspar-based porcelain compositions comprising tetragonal leucite typically have, when measured at 50 ° C. to 550 ° C .:
It has a coefficient of thermal expansion of approximately 18.6 × 10 ⁻⁶ / ° C. The melting (aging) temperature of the feldspathic porcelain composition according to the present invention is broadly in the range of about 800 ° C to about 1200 ° C, usually in the range of about 900 ° C to about 1150 ° C.

In another embodiment according to the present invention, a feldspathic porcelain having a discontinuous crystalline phase comprising cubic leucite that is substantially uniformly dispersed throughout the vitreous matrix is comprised of an alkali aluminosilicate powder. Heating the powder obtained from the mixture with the metal salt at a temperature of at least about 550 ° C. to about 1200 ° C. for a time sufficient to cause the formation of cubic leucite directly from the raw materials used; , Can be formed directly. Thus, for example, as shown in the Examples,
An 8 hour heat treatment, or an 8 hour heat treatment at 650 ° C., is sufficient to directly cause cubic leucite formation.

Further, according to another embodiment described herein, the feldspathic porcelain composition comprises from about 600 ° C. to about 110 ° C.
At temperatures in the range up to 0 ° C., from about 1 hour to about 48 hours
The heat treatment can be for up to an hour, preferably from about 1 hour to about 4 hours. As a result of this additional heat treatment operation, an increase in the amount of cubic leucite and / or an increase in the average particle size of cubic leucite was observed.

The properties of the feldspathic porcelain composition can be adjusted by applying known principles. For example, the coefficient of thermal expansion can be adjusted by adjusting the proportion of SiO ₂ and / or the proportion of alkali metal oxide, if desired. The melting point can be adjusted by adjusting the proportion of CaO and / or the proportion of alkali metal oxide. For example, Na ₂ O:
As the K ₂ O ratio increases, the melting point decreases. Applying these principles and fine-tuning the coefficient of thermal expansion and melting temperature of the feldspathic porcelain compositions described herein is well known to those skilled in the art of ceramics.

The low expansion feldspathic porcelain composition can be used in a wide range of dental restorations, such as all-ceramic restorations, porcelain restorations fused to metal, inlays, onlays, and veneers. It is anticipated that feldspathic porcelain compositions can be used as low expansion ceramic cores for all-ceramic restorations. In a particularly preferred embodiment,
Densely filling the powdered feldspathic porcelain composition and then sintering at a temperature from about 600 ° C. to about 850 ° C. to form a solid preform (greenware), or
If desired, it can be completely melted at a temperature from about 900 ° C. to about 1150 ° C. to form a solid preform (whiteware). These preforms can then be injection molded using a hot press method to form a dental restoration. The method begins by creating a wax repair. The wax model is removed from the mold and wrapped or surrounded by a material that solidifies on standing, such as "gypsum". Channels or openings communicate from the outer surface of the outer layer to the wax pattern. Wax is removed from the outer layer during the burn-out process. Feldspar dental porcelain preforms (greenware or whiteware) are manufactured by special hot pressing (eg, Wallingfo, CT).
rd Jeneric / Pentron Inc. Optimal ™ Autopress available from
(Trademark hot press), softened and forced into the outer layer opening under pressure. The softened preform material will fill the cavities created by the wax prototype. After cooling, the solidified ceramic is drawn from the outer layer. If desired, one or more layers of porcelain according to the invention can be applied to the ceramic core and / or the color can be baked on the surface of the restoration to simulate the color of the teeth.

The porcelain according to the present invention has a temperature of 50 ° C. to 550 ° C.
Up to about 16 × 10 ^-6
/ ° C, typically less than 12 × 10 ^-6 / ° C, so that a metal frame that also has a low coefficient of thermal expansion, such as a titanium metal alloy, or a low expansion ceramic, eg, Aluminum-containing porcelain (Vita
dur-N ™ is a trademark of Ba, California
(available from Vident, Idwin Park). One or more layers of the porcelain composition can be applied to the low expansion metal alloy frame or ceramic and fired separately. If desired
For example, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZnO, Ce
An opaque layer of feldspar porcelain, including an opacifier such as O ₂ , can be applied to the frame and fired. Then, instead or in combination, apply a tonal layer of feldspar porcelain containing one or more conventional pigments, for example, vanadates, manganates, chromates, or other transition metal compounds. Then, it can be colored to a desired color tone. If desired, a fluorescent generator such as, for example, cerium oxide, terbium oxide, yttrium oxide, or other conventional additives can also be incorporated into the porcelain to simulate the original dentition. The opaque and / or fluorescent toning layer (s) can then, if desired, be coated (before or after firing) with a feldspathic porcelain composition according to the invention. According to this method, it is possible to obtain a special effect, for example, a color tone at the tip of the restoration different from a color tone in the gingival region. The porcelain layer, for example,
The paste, in which the feldspathic porcelain powder is suspended in water, can be applied to the frame by conventional methods such as application to the frame, the desired profile can be shaped and then fired.

The porcelain can be used as an inlay, onlay, or veneer to replace amalgam, gold, or other porcelain. Feldspar porcelain according to the present invention can be prepared as an inlay, onlay, or veneer. The method uses a suitable heat resistant outer layer mold (eg, W.W., Connecticut) in which the porcelain powder is in the form of a water slurry.
allingford's Jeneric / Pentro
n Inc. Synvest sold by
(Trademark heat-resistant mold) and then firing the porcelain to a temperature in the range of about 800 ° C. to about 1200 ° C. to effect proper aging / melting of the porcelain. And If desired, one skilled in the art can use the foil method, in which a foil of platinum (0.001 inch) or other suitable foil adapted to the gypsum mold is used. Use, hold the porcelain in the proper geometry, remove the foil or porcelain from the gypsum mold, fire the porcelain, and perform the proper aging or melting of the porcelain. The resulting molten sample is placed on the prepared tooth, so that the smooth surface comes into contact with the adjacent tooth.

The following example illustrates the practice of the present invention.

[0044]

[Embodiment 1] Low expansion feldspathic glass containing the following components (Ame, Somerset, NJ)
riccan Thermocorp Corp. And rubidium nitrate (99%, Johnson Matth, Ward Hill, Mass.)
ey) were mixed in the same proportions.

[0045]

[Table 2] The powder is ground and mixed as mortar, placed in a porcelain crucible and heated at 450 ° C for 4 hours to exchange sodium and potassium ions extracted from feldspathic porcelain with rubidium ions released from rubidium nitrate. did. The resulting ion-exchanged powdered material was subsequently rinsed with water and dried at 150 ° C. for 2 hours. After drying,
X-ray diffraction was performed (FIG. 1), which revealed that the resulting material was amorphous.

The amorphous material is a dental porcelain reinforcing liquid (U
universal Porcelain ™ Enrichment Solution, Je, Wallingford, CT
neric / Pentron Inc. Was used to make a slurry. Put the slurry in the split mold,
Concentrated manually to form rods (4 × 8 × 25 mm). The rod is heated in a porcelain oven under a vacuum at a rate of 55 ° C./min.
The temperature was raised to 8 ° C., at which point the vacuum was released. It was kept at 1038 ° C. for 2 minutes under atmospheric pressure. X-ray powder diffraction of the sample revealed that cubic leucite was present in addition to the vitreous layer (FIG. 2). Inspection of the sample by scanning electron microscopy revealed the presence of small twin-free crystals with sizes ranging from about 0.5 μm to about 1 μm (FIG. 3).

Embodiment 2 FIG. ~ 5. And Comparative Example 1. ~ 2.
The effect of the duration of the ion exchange treatment on the percent crystallinity was investigated. Low expansion feldspathic glass and rubidium nitrate were newly mixed in the same ratio and heat-treated at 450 ° C. for 4, 8, 24, and 48 hours, respectively (Examples 2 to 5, respectively). 48 before firing at 1038 ° C
Since the X-ray diffraction of the powder ion-exchanged for a time showed only a vitreous layer, the amorphous property of the ion-exchanged material was confirmed. The powder was rinsed and dried as described in Example 1. Rods were prepared and heated to 1038 ° C. and aged at 1038 ° C. under atmospheric pressure for 2 minutes as described in Example 1. By X-ray powder diffraction of the sample,
It was found that the amount of the crystalline phase increased with the increase in the heat treatment time (FIGS. 4 to 7). The density of the rod was measured using the Archimedes method. From the density measurement results, it was confirmed that as the ion exchange treatment time increased, the crystal phase increased. The results are shown in Table 3 below. FIG. 5 is a graph showing the relationship between the heat treatment time and the average density.

[0048]

[Table 3] In Comparative Example 1, the feldspathic glass of Example 1 was manually concentrated into a rod (4 × 8 × 25 mm), and the rod was started from 600 ° C. in a porcelain oven under vacuum, starting at 600 ° C. per minute. 5
This corresponds to a rod obtained by heating up to 1038 ° C. at a temperature rising rate of 5 ° C. The vacuum was released at 1038 ° C. and the rod was fired at 1038 ° C. for 2 minutes under atmospheric pressure. Comparative Example 2 was made with Optec ™ high strength porcelain (Jeneric / P, Wallingford, CT).
entron Inc. Is manually concentrated to a rod (4 × 8 × 25 mm) in a porcelain oven under vacuum, starting at 600 ° C. and increasing to 1038 ° C. at a rate of 55 ° C./min. Corresponds to the rod obtained by raising the temperature. The vacuum was released at 1038 ° C. and the rod was fired at 1038 ° C. for 2 minutes under atmospheric pressure. According to the results of the density measurement, the ion exchange treatment significantly increased the density of the feldspathic glass as compared with the untreated control (Comparative Examples 1 and 2).
For example, it was found that ion exchange with metal ions such as rubidium occurred.

FIG. 9 shows the fine structure of the fifth embodiment. The average diameter of the cubic leucite crystals is 0.64 ± 0.02
μm, and the crystallinity percentage was 18.9 ± 2.8%. A few large tetragonal leucite crystals were observed. The number of these crystals was clearly higher than after 4 hours of ion exchange.

Embodiment 6 FIG. ~ 8. As described in Example 1, after ion exchange with rubidium nitrate for 48 hours,
The coefficient of thermal expansion was recorded for three samples (Examples 6 to 8) which were heated to 1038 ° C and baked at 1038 ° C under atmospheric pressure for 2 minutes. A typical thermal expansion curve is
As shown in FIG. The average coefficient of thermal expansion for Examples 6 to 8 is
8.7 when measured from 25 ° C. to 550 ° C.
88 ± 0.087 × 10 ⁻⁶ / ° C.

Embodiment 9 FIG. ~ 14. And Comparative Example 3. Furthermore, the effect of the heat treatment temperature on the particle size and percent crystallinity of the feldspathic porcelain composition was investigated. Glass powder was prepared by performing ion exchange with rubidium nitrate for 48 hours as described in Example 1. Sample (rod)
Was heated to 1038 ° C. as described in Example 1,
Baked at 1038 ° C. under atmospheric pressure for 2 minutes,
Heat treated at 800 ° C., 850 ° C., 900 ° C., 950 ° C., or 1038 ° C. for 4 hours. The results are shown in Table 4 below.

[0052]

[Table 4] According to X-ray diffraction, in the case of Examples 10 to 13, cubic leucite is present as the only crystal phase (FIGS. 11 and 1).
2, 13, and 14). By splitting several diffraction peaks, it was revealed in Example 14 that after treatment at 1038 ° C. for 4 hours, tetragonal rubidium leucite was present (FIG. 15). According to SEM examination, the average particle size is significantly greater for Examples 12 (Figures 16 and 17) and Example 13 (Figures 18 and 19) than for all other examples (p <
0.0003). Ion exchange promoted crystallization of cubic leucite in feldspathic glass, reaching 42.9% by weight, with an average particle size of 1.04 μm.

Examples 15 to 18 The effect of the ion exchange treatment time on the percentage of crystallinity of the sample subjected to the additional heat treatment was evaluated as follows.
Four separate mixtures of the powder described in Example 1 were
At 4, 8, 24, and 48 hours (Examples 15-18, respectively), predominantly sodium ions and less potassium ions extracted from feldspathic glass and released from rubidium nitrate. Exchange with rubidium ions. The resulting ion-exchanged powdered material is then rinsed separately,
Dry at 0 ° C. for 2 hours. The obtained amorphous material is a dental porcelain reinforcement liquid (Universal Porc)
Elaine build-up liquid, Jeneric, Wallingford, Connecticut
/ Pentron Inc. ), And separately mixed into a slurry, manually concentrated and placed in a split mold,
A rod (4 × 8 × 25 mm) was formed. The bar was heated in a porcelain oven under vacuum at 600 ° C. and at a rate of 55 ° C./min to 1038 ° C., at which point the vacuum was released. The rod was kept at 1038 ° C. under atmospheric pressure for 2 minutes. The rods are also 80
Treated at 0 ° C. for 4 hours. According to X-ray powder diffraction,
The amount of crystalline phase increased with increasing ion exchange treatment time (FIGS. 20, 21, 22 and 23).

Example 19 The following embodiment illustrates the incorporation of rubidium into a cubic potassium leucite network after ion exchange between feldspathic glass and rubidium nitrate.

Crystallization of cubic leucite in feldspar glass is promoted by low-temperature ion exchange between feldspathic glass powder and rubidium nitrate. It is assumed that rubidium acts as a crystal nucleating agent and is subsequently included in the cubic potassium leucite network. Since rubidium ions are larger than potassium ions, substituting part of potassium ions with rubidium in the leucite structure increases the lattice constant and slightly changes the lattice constant. Thus, direct evidence for the presence of rubidium in the cubic potassium leucite network can be obtained by measuring the lattice constant of cubic leucite (Martin and Lagache (197).
5)). It was shown that there is a linear relationship between the amount of rubidium or cesium in the tetragonal leucite network and the cell volume.

[0056] lattice constant α is 13.43 angstrom in the case of cubic potassium leucite (1 angstrom 10 ^-10 m) equal to (Hermansson
And Carlsson (1978)) equals 13.60 Å for cubic rubidium leucite (Kosorukov and Nadel (1978)).
85)). Potassium ion with rubidium ion 100
The change of the lattice constant corresponding to the% substitution is 0.17
Angstrom.

Table 5 summarizes the lattice constants of cubic leucite in the low expansion feldspathic glass of Example 1 obtained by ion exchange with rubidium and the calculated values of the amount of potassium replaced by rubidium. Shown in

[0058]

[Table 5] It can be seen that the amount of rubidium incorporated into the potassium leucite network increases with increasing duration of the ion exchange treatment and with increasing temperature of the ion exchange treatment. The crystalline phase formed in all ion-exchanged feldspathic porcelain is cubic leucite having the following chemical formula:

[0059]

If the amount of potassium displaced by rubidium in the Rb _X K _(1-X) Si ₂ O ₆ leucite network is known, the weight percent of rubidium in the network can be calculated. For example, material D
, 10% of potassium sites are occupied by rubidium ions, which is 3.8% by weight in leucite
Is converted to rubidium. Material D has 37.9% Rb
/ K leucite, resulting in the ceramic material containing 1.44% rubidium.

When the ceramic is further heat treated at 1038 ° C. for 4 hours, the amount of rubidium occupying potassium sites in the leucite network is reduced and at the same time a second phase appears in the material. This second phase is tetragonal rubidium leucite, with almost 100% potassium sites occupied by rubidium. This result can be explained by the fact that high temperature or relatively long treatment promotes more complete diffusion of rubidium ions into the cubic potassium leucite network.

Embodiment 20 FIG. The low expansion feldspathic glass of Example 1 and rubidium nitrate were mixed at the same ratio, and the mixture was mixed at 450 ° C., 500 ° C., 525 ° C., 550 ° C., 575 for 48 hours.
Heat treated at ℃. One mixture was heat treated at 650 ° C. for 8 hours. The powder was rinsed to remove rubidium nitrate and dried at 150 ° C for 2 hours. X-ray analysis was performed on the dried powder. A ceramic rod (25 × 6 × 8 mm) is formed using a split mold, and
At temperatures ranging from 038 ° C to 1150 ° C, 2
Bake for 10 minutes to 10 minutes (Table 6).

[0062]

[Table 6] For the rods, thermal expansion and contraction between 25 ° C. and 650 ° C. were performed at a rate of 3 ° C./min and 10 ° C./min.
The cooling rate was recorded. The powdered sample was analyzed by X-ray diffraction. Scanning microscopy was performed on the finished sample. Four micrographs were used for each sample to evaluate the percent crystallinity.

According to the X-ray diffraction (XRD) analysis of the crude powder (FIGS. 24A to 24F), the sample was 450
After the ion exchange treatment at ℃, 500 ℃ and 525 ℃, was amorphous (glassy substrate only). Cubic leucite was present in a small amount in the powder that had been ion-exchanged at 550 ° C. and in a large amount in the powder that had been ion-exchanged at 575 ° C. The powder ion-exchanged at 650 ° C. for 8 hours yields a very large amount of cubic leucite (R).
_{b X K (1-X)} Si 2 O 6) and containing a small amount of tetragonal rubidium leucite. Calculations from lattice constant measurements indicate that rubidium occupies 25.29% of the potassium sites in the cubic leucite network. The results obtained from the X-ray diffraction analysis after one firing are summarized in Table 7 and FIGS. 25 (a) to 25 (f).

[0064]

[Table 7] Table 8 shows the results of the thermal expansion coefficient measurement.

[0065]

[Table 8] It is clear from microphotographs (FIGS. 26 to 29) that the temperature of the ion exchange treatment promotes the formation of cubic leucite crystals in the vitreous composition.

High magnification enlargement confirmed that small size crystals (approximately 2 μm) were present in the material ion-exchanged at 575 ° C. for 48 hours (FIG. 3).
0). According to the dilatometer measurements, the thermal expansion of the ceramic increases with increasing ion exchange temperature. However, cubic leucite has a very low coefficient of thermal expansion (approximately 3 × 10 ⁻⁶ /) at temperatures from 625 ° C. to 900 ° C.
° C). Therefore, there is no possibility that the coefficient of thermal expansion increases due to an increase in cubic leucite in the ceramic. One hypothesis explaining this phenomenon is that in high-temperature ion exchange, the glassy substrate is deprived of alkali ions such as sodium and potassium by the ion exchange treatment, resulting in an increase in the thermal expansion of the material. That is.

Further, variations and modifications of the present invention will become apparent to those skilled in the art from the foregoing description and are encompassed by the following claims.

[Brief description of the drawings]

FIG. 1 is a diagram showing an X-ray diffraction pattern of an amorphous material produced by a method of Example 1 of the present invention.

FIG. 2 is a view showing an X-ray diffraction pattern of a feldspar-based porcelain composition produced by the method of Example 1 of the present invention.

FIG. 3 is a view showing a SEM micrograph of the feldspathic composition of FIG. 2;

FIG. 4 is a view showing an X-ray diffraction pattern of a feldspathic composition for 4 hours in an ion exchange heat treatment.

FIG. 5 is a view showing an X-ray diffraction pattern of a feldspathic composition for 8 hours of ion exchange heat treatment.

FIG. 6 is a view showing an X-ray diffraction pattern of a feldspathic composition for 24 hours of an ion exchange heat treatment.

FIG. 7 is a view showing an X-ray diffraction pattern of a feldspathic composition for 48 hours of an ion exchange heat treatment.

FIG. 8 is a graph showing the relationship between the average density of the feldspathic dental porcelain according to the present invention and the ion exchange heat treatment time.

FIG. 9 shows a sample obtained by starting from 600 ° C., increasing the temperature to 1038 ° C. at a heating rate of 55 ° C./min, holding at that temperature for 2 minutes, and performing heat treatment after the ion exchange treatment for 48 hours. It is a SEM micrograph.

FIG. 10 is a graph showing a typical thermal expansion curve of a feldspathic porcelain composition according to the present invention.

FIG. 11 is a view showing an X-ray diffraction pattern of a feldspathic composition at a heat treatment temperature of 800 ° C.

FIG. 12 is a view showing an X-ray diffraction pattern of a feldspathic composition at a heat treatment temperature of 850 ° C.

FIG. 13 is a view showing an X-ray diffraction pattern of a feldspathic composition at a heat treatment temperature of 900 ° C.

FIG. 14 is a view showing an X-ray diffraction pattern of a feldspathic composition at a heat treatment temperature of 950 ° C.

FIG. 15 shows the X of the feldspathic composition at a heat treatment temperature of 1038 ° C.
It is a figure which shows a line diffraction pattern.

FIG. 16 is a diagram showing a 2000 × SEM micrograph of the sample in FIG. 12;

17 is a diagram showing a 4000 × SEM micrograph of the sample of FIG. 12;

FIG. 18 is a diagram showing a 2000 × SEM micrograph of the sample of FIG. 13;

19 is a diagram showing a 4000 × SEM micrograph of the sample of FIG. 13;

FIG. 20 is a view showing an X-ray diffraction pattern of a sample additionally heat-treated to the feldspathic composition for 4 hours of the ion-exchange heat treatment.

FIG. 21 is a view showing an X-ray diffraction pattern of a sample additionally heat-treated to the feldspathic composition for 8 hours of the ion-exchange heat treatment.

FIG. 22 is a view showing an X-ray diffraction pattern of a sample additionally heat-treated to a feldspathic composition for 24 hours in an ion-exchange heat treatment.

FIG. 23 is a view showing an X-ray diffraction pattern of a sample additionally heat-treated to a feldspathic composition for 48 hours in an ion-exchange heat treatment.

FIG. 24 shows X-ray diffraction patterns of unpurified ion exchange-treated powder at various temperatures.

FIG. 25 is a diagram showing X-ray diffraction patterns at various temperatures of a ceramic sample produced from the ion-exchanged powder after one firing.

FIG. 26 is an SEM micrograph showing the formation of cubic leucite crystals with an increase in the ion exchange treatment temperature.

FIG. 27 is an SEM micrograph showing the formation of cubic leucite crystals as the ion exchange treatment temperature is increased.

FIG. 28 is an SEM micrograph showing the generation of cubic leucite crystals as the ion exchange treatment temperature is increased.

FIG. 29 is an SEM micrograph showing the generation of cubic leucite crystals as the ion exchange treatment temperature is increased.

FIG. 30 is a SEM micrograph of a ceramic sample produced from the alkali aluminosilicate powder after the ion exchange treatment at 575 ° C. for 48 hours.

Claims (20)

[Claims] 1. A feldspathic porcelain composition, comprising a continuous vitreous matrix phase and cubic leucite stabilized by at least one of cesium, calcium, strontium, barium or thallium. And a discontinuous crystalline phase that is substantially uniformly dispersed, and having a melting temperature of about 800 ° C to about 1200 ° C. 2. The feldspathic porcelain composition of claim 1, wherein the cubic leucite is from about 0.5 μm to about 1 μm.
Feldspar porcelain composition characterized by having an average diameter in the range of up to 0 μm. 3. The composition of claim 2, wherein the cubic leucite has an average diameter ranging from about 1 μm to about 4 μm. 4. The feldspathic porcelain composition of any of claims 1 to 3, wherein the discontinuous crystalline phase comprises about 5% to about 65% by weight of the feldspathic porcelain composition. A feldspar-based porcelain composition characterized by the fact that: 5. The feldspar-like porcelain composition according to claim 1, wherein the feldspathic vitreous matrix phase comprises:
From about 65% to about 72% by weight of SiO ₂ ,
Comprising from about 5% to about 15% by weight of Al ₂ O ₃ , from about 5% to about 10% by weight of K ₂ O, and from about 5% to about 10% by weight of Na ₂ O. Feldspar-based porcelain composition. 6. The feldspar-like porcelain composition according to any one of claims 1 to 5, wherein the feldspathic vitreous matrix phase comprises:
Further, from about 0% to about 2% by weight of CaO,
MgO from wt% to about 0.5 wt.%, CeO ₂ from about 0 wt% to about 0.5 wt%, and that from about 0 wt% including Li ₂ O of less than about 0.5 wt% Feldspar porcelain composition characterized. 7. A dental porcelain restoration comprising the feldspathic porcelain composition according to any one of claims 1 to 6. 8. A dental porcelain restoration comprising a metal frame or ceramic core and at least one coating fused thereon, wherein the coating is feldspathic according to any of the preceding claims. A dental porcelain restoration comprising a porcelain composition. 9. An inlay, an onlay or a veneer comprising the feldspathic porcelain composition according to any one of claims 1 to 6. 10. A method for preparing a feldspathic porcelain composition, comprising a vitreous material consisting of SiO ₂ , Al ₂ O ₃ and K ₂ O, and rubidium, cesium, calcium, strontium, barium or thallium. Forming an alkali aluminosilicate powder containing at least one metal salt, and at least one alkali metal salt; heating the alkali aluminosilicate powder to be released from the alkali cation and the metal salt Performing ion exchange with metal cations to produce a feldspathic porcelain composition having a continuous vitreous matrix phase and a discontinuous crystalline phase including cubic leucite. For preparing a feldspathic porcelain composition. 11. The method for preparing a feldspar porcelain composition according to claim 10, wherein the metal salt is rubidium nitrate. 12. A method for preparing a feldspathic porcelain composition, comprising vitreous comprising SiO ₂ , Al ₂ O ₃ , K ₂ O and Na ₂ O, and cesium, calcium, strontium, barium or Forming an alkali aluminosilicate powder containing at least one metal salt of thallium; heating the alkali aluminosilicate powder to carry out ion exchange between an alkali cation and a metal cation released from the metal salt; Producing a feldspathic porcelain composition having a continuous vitreous matrix phase and a discontinuous crystalline phase including cubic leucite, and preparing a feldspathic porcelain composition. Method. 13. The method for preparing a feldspar porcelain composition according to claim 12, wherein the alkali aluminosilicate powder further contains an alkali metal salt. . 14. The method of any of claims 10, 11, or 13, wherein the alkali metal salt is present in an amount ranging from about 1% to about 10% by weight of the metal salt. A method for preparing a feldspar-based porcelain composition, characterized by comprising: 15. The method for preparing a feldspathic porcelain composition according to any one of claims 10 to 14, wherein the alkali aluminosilicate powder contains the vitreous and the metal salt in an amount of about 20:80 to about 80. : A method for preparing a feldspathic porcelain composition, wherein the composition is formed by mixing at a weight ratio in the range of up to 20. 16. The method of preparing a feldspathic porcelain composition according to any of claims 10 to 15, wherein the feldspathic glass comprises from about 65% to about 72% by weight of Si.
O ₂ , from about 10% to about 15% by weight of Al ₂ O ₃ ,
A process for preparing a feldspathic porcelain composition comprising about 5% to about 10% by weight K ₂ O, and optionally about 5% to about 10% by weight Na ₂ O. 17. The method of preparing a feldspathic porcelain composition according to any of claims 10 to 16, wherein the feldspathic glass further comprises from about 0% to about 2% by weight of Ca.
O, from about 0% to about 0.5% by weight MgO, about 0%
Wt.% To about 0.5 wt.% CeO ₂ , and about 0 wt.
Process for the preparation of feldspathic porcelain composition which comprises a Li ₂ O from% to about 0.5 wt%. 18. The method of preparing a feldspathic porcelain composition according to claim 10, further comprising the step of forming the feldspathic porcelain composition during a dental restoration. For preparing a feldspathic porcelain composition. 19. The method for preparing a feldspar porcelain composition according to claim 18, wherein the restoration further comprises a metal frame or a ceramic core. . 20. The method for preparing a feldspar-like porcelain composition according to any of claims 10 to 19, further comprising the step of forming the feldspar-like porcelain composition during inlay, onlay, or veneering. A method for preparing a feldspar-based porcelain composition, comprising: